The teen who was hospitalized with a severe vaping-related respiratory illness in London, Ont., did not use a cannabis-related product, the region's medical officer of health told CBC News.

The high-school aged person who fell ill earlier this year was in intensive care and has recovered.

Dr. Chris Mackie, medical officer of health and CEO of Middlesex-London Health Unit, said the person hadn't been vaping cannabis.

"This person was not using those products" that include tetrahydrocannabinol (THC, the main active ingredient in cannabis that gives users a high), Mackie said in an interview Friday. "The person was vaping fairly heavily with a nicotine-based product."

It is important for people to understand that the severe respiratory illness associated with vaping "is not a remote risk" but very real in Canada, he said.

A local physician reported an "incident" involving an e-cigarette product to a voluntary national database to flag potential problems related to consumer products.

Ontario teen was on life-support after respiratory illness linked to vaping
But the database isn't detailed enough to classify someone as a confirmed or probable patient, said Dr. Theresa Tam, Canada's chief medical officer of health.

There are three incident reports from across the country under investigation from the database, with at least one dating back to 2018, Tam said.

Tam did not reveal the health status of the individuals, their ages or where they're located. Rather, provinces still need to gather a thorough history of a patient's potential vaping, clinical symptoms and information on the products and devices used before any cases in the country could be confirmed.

Based on a Canadian version of the U.S. Centers for Disease Control's case definitions, Tam said physicians are on the lookout for patients with a history of vaping or e-cigarette use in the previous 90 days reporting respiratory illness such as:

Cough.
Shortness of breath.
Chest pain.
Fever.
Sometimes nausea and gastrointenstinal upset.
Doctors would first rule out any other infectious diseases before considering it a vaping-related case. As more health-care providers routinely ask people whether they vape, more suspected cases are expected to come to light.

"If you don't vape, don't start," Tam said. "Youth, pregnant women and non-smokers should not vape. Those who do vape should get their product from a regulated, approved source — for example for nicotine-vaping products. There are no current regulated sources of cannabis or THC-containing products."

Tam said while cannabis and THC-containing products are readily available on the grey market, next month's regulations should afford protections. For instance, Health Canada will introduce rules on what ingredients can be in THC vape liquids and on how the products and devices are produced and monitored.

The science behind why vaping is becoming so popular in Canada
Walmart to stop selling electronic cigarettes at its U.S. stores

In the U.S., 530 confirmed and probable cases have been reported in 38 states and one U.S. territory, up from 380 a week ago. The country's eighth death was reported by state officials in Missouri on Thursday.

The CDC said most patients have reported a history of using e-cigarette products containing THC, many reported using THC and nicotine, and some have reported the use of e-cigarette products containing only nicotine.

'Paddling upstream' against marketing
No single device, ingredient, additive or pathway to illness has been identified in the U.S., federal officials there stressed.

Similarly, Mackie said his health unit is not identifying the brand used in the London case, because doing so could implicate one specific product when the international evidence isn't pointing that way.

Mackie said since Wednesday's news conference, he's received a backlash on social media from people who support vaping.

"There is really a firm — I would say vicious — campaign on social media to criticize anyone speaking out against vaping," Mackie said.

Given that up to 90 per cent of teens in some of his city's schools report vaping, Mackie isn't deterred.

"We're really paddling upstream with the amount of marketing of vaping that there is, and especially of those flavoured products which really appeal to youth."